The present invention relates to impact type dot matrix print heads and more particularly to impact dot matrix print heads of the free flight, ballistic type in which a novel flexible parasol is utilized to permit armature biasing force to be established and maintained independently of the adjustable spacing between the armature and the free flight print wires.
Dot matrix printers are typically comprised of a plurality of print wires whose printing ends are arranged in linear fashion to selectively print dots at dot positions arranged along an imaginary vertical line. A print wire housing is provided for mounting the print wires in a reciprocating fashion so that their forward ends may impact a paper document, typically through an inked ribbon. The rearward ends of the print wires are reciprocally driven by solenoid assemblies selectively energized to cause only those desired print wires to impact the paper document. In order to be assured that the proper amount of driving force will be imparted by each solenoid to its print wire, critical adjustments are typically required. In an effort to simplify the amount and precision of such adjustments, print heads of the type described in U.S. Pat. No. 3,929,214 have been developed which enable the print wire ends to be adjusted relative to the armatures through one single adjustment operation permitting all of the print wires and armatures to be adjusted simultaneously. However, print heads of this type have the drawback of altering the biasing force imposed upon the armature elements whereupon the appropriate positioning between the armature and the print wire results in a biasing force imposed upon each armature.